<?php 

trait A
{
    public static $name = '芸芸';
    public static function demo()
    {
        echo 'A中的demo<br>';
    }
    abstract public function test();
}


class User
{
    use A;
    public function test()
    {
        
    }
}



User::demo();
echo User::$name;

echo '<hr>';
$u = new User();
$u->demo();
// echo $u->name;
